/*
 *   This program is free software: you can redistribute it and/or modify
 *   it under the terms of the GNU General Public License as published by
 *   the Free Software Foundation, either version 3 of the License, or
 *   (at your option) any later version.
 *
 *   This program is distributed in the hope that it will be useful,
 *   but WITHOUT ANY WARRANTY; without even the implied warranty of
 *   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *   GNU General Public License for more details.
 *
 *   You should have received a copy of the GNU General Public License
 *   along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

/*
 *    PotentialClassIgnorer.java
 *    Copyright (C) 2003-2012 University of Waikato, Hamilton, New Zealand
 *
 */

package weka.filters.unsupervised.attribute;

import java.util.Enumeration;
import java.util.Vector;

import weka.core.Instances;
import weka.core.Option;
import weka.core.OptionHandler;
import weka.core.Utils;
import weka.filters.Filter;

/**
 * This filter should be extended by other unsupervised attribute filters to
 * allow processing of the class attribute if that's required. It the class is
 * to be ignored it is essential that the extending filter does not change the
 * position (i.e. index) of the attribute that is originally the class attribute
 * !
 * 
 * @author Eibe Frank (eibe@cs.waikato.ac.nz), Mark Hall
 *         (mhall@cs.waikato.ac.nz)
 * @version $Revision$
 */
public abstract class PotentialClassIgnorer extends Filter implements OptionHandler {

    /** for serialization */
    private static final long serialVersionUID = 8625371119276845454L;

    /** True if the class is to be unset */
    protected boolean m_IgnoreClass = false;

    /** Storing the class index */
    protected int m_ClassIndex = -1;

    /**
     * Returns an enumeration describing the available options.
     * 
     * @return an enumeration of all the available options.
     */
    @Override
    public Enumeration<Option> listOptions() {

        Vector<Option> result = new Vector<Option>();

        result.addElement(new Option("\tUnsets the class index temporarily before the filter is\n" + "\tapplied to the data.\n" + "\t(default: no)", "unset-class-temporarily", 1, "-unset-class-temporarily"));

        return result.elements();
    }

    /**
     * Parses a list of options for this object.
     * 
     * @param options the list of options as an array of strings
     * @throws Exception if an option is not supported
     */
    @Override
    public void setOptions(String[] options) throws Exception {
        setIgnoreClass(Utils.getFlag("unset-class-temporarily", options));
    }

    /**
     * Gets the current settings of the filter.
     * 
     * @return an array of strings suitable for passing to setOptions
     */
    @Override
    public String[] getOptions() {

        Vector<String> result = new Vector<String>();

        if (getIgnoreClass()) {
            result.add("-unset-class-temporarily");
        }

        return result.toArray(new String[result.size()]);
    }

    /**
     * Sets the format of the input instances. If the filter is able to determine
     * the output format before seeing any input instances, it does so here. This
     * default implementation clears the output format and output queue, and the new
     * batch flag is set. Overriders should call
     * <code>super.setInputFormat(Instances)</code>
     * 
     * @param instanceInfo an Instances object containing the input instance
     *                     structure (any instances contained in the object are
     *                     ignored - only the structure is required).
     * @return true if the outputFormat may be collected immediately
     * @throws Exception if the inputFormat can't be set successfully
     */
    @Override
    public boolean setInputFormat(Instances instanceInfo) throws Exception {

        boolean result = super.setInputFormat(instanceInfo);
        if (m_IgnoreClass) {
            m_ClassIndex = inputFormatPeek().classIndex();
            inputFormatPeek().setClassIndex(-1);
        }
        return result;
    }

    /**
     * Gets the format of the output instances. This should only be called after
     * input() or batchFinished() has returned true. The relation name of the output
     * instances should be changed to reflect the action of the filter (eg: add the
     * filter name and options).
     * 
     * @return an Instances object containing the output instance structure only.
     * @throws NullPointerException if no input structure has been defined (or the
     *                              output format hasn't been determined yet)
     */
    @Override
    public Instances getOutputFormat() {

        if (m_IgnoreClass) {
            outputFormatPeek().setClassIndex(m_ClassIndex);
        }
        return super.getOutputFormat();
    }

    /**
     * Returns the tip text for this property
     * 
     * @return tip text for this property suitable for displaying in the
     *         explorer/experimenter gui
     */
    public String ignoreClassTipText() {
        return "The class index will be unset temporarily before the filter is applied.";
    }

    /**
     * Set the IgnoreClass value. Set this to true if the class index is to be unset
     * before the filter is applied.
     * 
     * @param newIgnoreClass The new IgnoreClass value.
     */
    public void setIgnoreClass(boolean newIgnoreClass) {
        m_IgnoreClass = newIgnoreClass;
    }

    /**
     * Gets the IgnoreClass value. If this to true then the class index is to unset
     * before the filter is applied.
     * 
     * @return the current IgnoreClass value.
     */
    public boolean getIgnoreClass() {
        return m_IgnoreClass;
    }
}
